Part 6

On occasion, this insect, Acrobasis juglandis (LeB.), develops to damaging numbers and causes economic injury. Early in the spring the larva feeds on unfolding leaves and buds. It may prevent leaf development for weeks, resulting in a greatly decreased yield of nuts.

The adult is a dark gray moth marked with brown. Its forewings, which have a spread of about two-thirds inch, are gray with black blotches. There is a reddish mark near the base of the forewings.

The immature larva is brown, but changes to dark green as it develops to a length of one-half inch. It has a shiny, brownish black head and is enclosed in a gray case which completely covers the body and is borne in a position nearly perpendicular to the leaf on which the larva is feeding.

The pecan leaf casebearer overwinters as an immature larva in a hibernaculum around a bud. It emerges in late March or early April as the buds open. The larvae mature in April, May and June and transform into pupae within their gray cases, Figure 15. The moths are present from May until early August. Eggs are deposited during this period on the underside of the leaves. The larvae which hatch from these eggs develop slowly, and do not attain a length of more than one-sixteenth inch during that season. They construct little winding cases in which they live. Their feeding produces irregular blotches on the leaf surface, Figure 16. Before the leaves drop in the fall, the larvae migrate to the buds, and construct their overwintering hibernacula. Only one generation is completed each year.

Control.—Control of this insect is accomplished by spraying for the pecan nut casebearer. See spray schedule, page 4. The insecticides recommended for nut casebearer control also reduce infestations of the leaf casebearer.

PECAN PHYLLOXERA

The pecan phylloxera, Phylloxera devastatris Perg., and the pecan leaf phylloxera, P. notabilis Perg., produce galls on the new growth of pecans. Leaves, twigs and nuts may be affected.

The galls are conspicuous swellings, Figure 17, which attain a size of from one-tenth to 1 inch in diameter. They are caused by a soft-bodied insect which is closely related to aphids.

The winter is passed in the egg stage in crevices in the bark. In the spring, the egg hatches and the tiny nymph feeds on the tender, young growth, apparently secreting a substance which stimulates the plant tissues to develop into galls.

After the nymph reaches maturity, a number of eggs are deposited inside the gall. The young nymphs of the succeeding generation develop within the gall, which splits open in 1 to 3 weeks, liberating them. Several generations follow during the summer and fall, as long as there is fresh young growth on the tree. From 4 to 5 weeks are required for each generation.

Control.—The dormant oil spray recommended for obscure scale control will prevent the development of phylloxera. If dormant oil is not applied, use 2 pints of nicotine sulfate plus 6 pounds of soap; 3 pounds of 25 percent malathion wettable powder; or two and a half pounds of 10 percent gamma isomer BHC wettable powder per 100 gallons of water when the leaves are one-third grown.

SAWFLIES

Sawfly larvae, Periclista sp. and others, feed on the foliage of pecans during April and early May. The larvae, which are light green, chew holes in the leaves. Usually the midrib and veins are left intact, giving the leaflets a lacy appearance, Figure 18.

The adults closely resemble wasps, except that they are not “wasp-waisted.”

Control.—The larvae may be controlled with an application of 2 pounds of 50 percent DDT wettable powder or 1 pound of 25 percent parathion wettable powder per 100 gallons of water.

MAY BEETLES

Many species of May beetles may damage pecans early in the spring. The beetles appear only at night and spend the day concealed beneath the surface of the soil. They feed on the young leaves and prevent the foliage from developing.

Beetles of the most common species are one-half to three-fourths inch long and shiny dark brown. They are attracted to lights and are observed commonly on porches or screen doors at night. The larvae are the grubworms, or white grubs, which feed in the soil on the roots of many plants.

The female beetle deposits eggs in the soil, where the larva develops. Most species require two summers for the larva to mature. Pupation is accomplished in a cell which is constructed in the ground in the fall of the second year. The beetles emerge the following spring. Both larvae and adults may be found in the soil during the winter.

Control.—May beetles are usually a problem in orchards which are not cultivated because the larvae feed on the roots of the sod cover. Cultivation of the orchard periodically will reduce the food supply of the grubs, and smaller infestations of adults will appear the following year. Where cultivation is not feasible, sprays will control the adults. Apply 2 pounds of 50 percent DDT wettable powder; 4 pounds of lead arsenate; or 1 pound of 25 percent parathion wettable powder per 100 gallons of water when damage by this insect is severe.

PECAN CIGAR CASEBEARER

The pecan cigar casebearer, Coleophora caryaefoliella (Clem), may be damaging in some years. The larva feeds on the leaves, producing tiny holes. It constructs a light brown, cigar-shaped case about one-fourth inch in length which encases it throughout development.

Control.—The spray applied for control of the nut casebearer will usually prevent significant injury by the cigar casebearer. See spray schedule, page 4.

FALL WEBWORM

The webs produced by the fall webworm, Hyphantria cunea (Drury), are familiar to everyone. Leaves are eaten by the larvae which live in loosely woven, dirty white webs, Figure 19.

The adult is a white moth which may have black or brown spots on the forewing. Its wings have a span of about 1 inch.

The larvae are pale yellow spotted with black. They attain a length of 1 inch when full grown and are covered with long black and white hairs.

The insect overwinters as a pupa in lightly woven cocoons in debris on the soil or under the bark. In the spring the adults emerge and lay masses of greenish white eggs on the leaves. The caterpillars which hatch from the eggs feed on the leaves in colonies under webs which they construct. After feeding for a month to 6 weeks, the larvae crawl down the tree and pupate in loose cocoons in debris, under bark, or in loose soil. Adults appear during the summer and deposit eggs for the second generation. The larvae of this generation feed extensively until fall, crawl down the tree and pupate for the winter.